Pair of socks? (3-3)
(Other definitions for one-two that I've seen before include "Pair of punches with both hands in quick succession" , "Pair of blows in boxing" , "Blow using fists' digits" , "Interpassing at football - left-right at boxing" , "Boxing or soccer manoeuvre" .)
(Another definition for onetwo that I've seen is " Punches".)